Hydraulic control system for a stoker motor



Aug. 17, 1937. s, MORTON I 2,090,583

HYDRAULIC CONTROL SYSTEM FOR A STOKER MOTOR Original Filed May 51, 193?. 2 Sheets-Sheet l Aug. 17, 1937. H, s MORTON 2,090,583

HYDRAULIC CONTROL SYSTEM FOR A STOKER MOTOR Original Filed May 31, 1932 2 Sheets-Sheet 2 Patented Aug. 17, 1937 HYDRAULIC CONTROL SYSTEM FOR A STOKER MOTOR Harold S. Morton, Minneapolis, Minn, assignor to Stott Briquet Company, Inc., St. Paul, Minn, a corporation of Delaware Application May 31, 1932, Serial No. 614,483 Renewed July 14, 1937 9 Claims.

My invention relates to an improvement in hydraulic control systems, of a type particularly adaptable for use in the control of hydraulic stoker mechanisms to feed fuel to a furnace.

My invention relates to a means adapted to control the hydraulic pressure to the operating cylinder of the stoker or cylinders, so that should any obstruction take place in the fuel hopper or in front of the ram so as to impair the operation thereof, the controller will automatically relieve the pressure or reverse the stoker operating piston and even cause the same to continue to operate with a shorter than normal stroke if the obstruction interferes with the operation of the stoker ram. In this manner, I provide a controlling means which operates automatically and which has a means of signalling to indicate that the stoker piston is not operating normally.

The controller in my system for regulating the operation of the working piston is provided with means which is of a simple nature, quick to function to relieve excessive hydraulic pressure, and to automatically direct the hydraulic pressure away from either side of the stoker piston should an obstruction take place. The controller also has means to cause the stoker piston to reciprocate back and forth with a shorter stroke so as to continue to feed some fuel to the furnace, even though there is. a partial obstruction of the full normal stroke for which the stoker is set to operate, and at the same time sound an alarm to indicate that the stoker is not operating normally, thereby providing a means for controlling the operation of the piston of a stoker automatically and without requiring personal attention of the fireman to closely watch the same.

It is the purpose of my invention to form the reversing valve of a unitary nature with three In the reversing action of the unitary piston in one direction, one of the hollow end pistons of the unitary piston is forced by one of the auxiliary pistons which I provide in my controller by the opening of a high pressure port communi- 1 eating with the plunger piston. A spring between the hollow end of the unitary piston and the valve piston is compressed during this movement. When the Valve piston passes center position, starting to change the direction of flow 55 of oil to the cylinder, the pressure tending to force the end piston on the auxiliary piston against the valve piston is cut off, but the spring expands, throwing the valve piston the remainder of the distance to reverse the flow.

It is a further object of my controller to provide a means to eliminate the necessity of closed pressure tanks for forcing the unitary valve piston past center in operation and this I accomplish by the separate auxiliary pistons which are positioned in an enlarged piston chamber at either end of the unitary valve piston. The spring means provided between the valve piston and the auxiliary piston acts to provide the necessary expansion to obviate the necessity of closed pressure tanks such as I have used heretofore in the control of the reversing valve to move the same beyond center operating position, as illustrated in my Patent No. 2,031,120.

These features, together with other details and objects of my controller will be more fully and clearly set forth.

In the drawings forming a part of the specification:

Figure 1 illustrates diagrammatically a stoker and fuel hopper for feeding fuel to a fire pot of a furnace, showing a portion thereof in section with the operating cylinder for the stoker plunger and showing my controller connected to the operating piston by a series of pipes.

Figure 2 illustrates diagrammatically a section of my controller and a portion of the operating piston which operates the plunger of the stoker illustrated in Figure 1.

Figure 3 is a cross-sectional viewon the line 33 of Figure 2.

My control valve A is adapted to be submerged in the oil tank B. Oil from the tank B is drawn through the pipe II! to the pump C, which forces a steady supply of oil to the valve A through the pipe II. The valve A acts automatically to reverse the direction of travel of the piston [2 within the plunger cylinder D each time the piston l2 reaches the end of its stroke. The oil at high pressure from the pump C is first directed through the pipe l3 to one end of the cylinder D to force the piston 12 in one direction, the pipe I4 at the other end of the cylinder D being exposed to exhaust pressure only due to the expulsion of the oil from the cylinder D by the piston back into the tank B. When the piston reaches the end of its stroke, the valve acts automatically to expose the pipe [4 to the high pressure from the pipe C, opening a passage between the pipe l3 and the tank B, whereby the oil may be expelled from the cylinder D on the low pressure side of the piston.

As illustrated in Figure 1 of the drawings, the cylinder D is positioned. adjacent a hopper E for coal, and the reciprocation of the piston I2 is carried by'the piston rod I5 to reciprocate the plunger I6 which acts to force the coal from the hopper E into the fire pot ll of the boiler F. Fuel is thus fed in measured intervals into the 10 bottom of the boiler F to continuously keep a The valve A includes a unitary reversing piston valve I8. The central piston I9 of the valve I8 acts to cut off one or the other of the ports 28 and 22, which are formed in the piston valve cylinder 23 on each side of the center thereof;

from the centrally positioned port 24. The port 24 is connected with the pipe I I leading from the. pump C, whereas the ports 28 and 22 are 0 connected with the ends of the pipes I3 and I4 When the valve. I8 moves to the j respectively.

left, as illustrated in Figure 2 of the drawings, an 'oil passage is formed between the central piston I9and theright end piston 25 from the pump. 25 C and the .port 24 to the pipe I4, and the pres- 7 sure from the pump is transmitted to the right end of the cylinderD, tending tomove the piston I2.to the left. Similarly, when the valve I8 is moved'to its right extreme position, a passage is formed between the central piston 19 and the left end piston 26, from the pump C through the port 24 to the port 20 and the pipe I3, transmitting high pressure oil from the pump C to the left end of the cylinder D, forcing the piston I2 to the right.

Simultaneously with theopening of the passage from the pump C to the pipe I4 in the aforementioned manner, a passage is'opened between the central piston I9 and the leftend piston 26 to the exhaust opening 21.

Thus, the oil to the left of the piston I2 as the piston moves to the left, may be forcedthrough the pipe I3 and its port 20 through the annular port 28 tothe exhaust opening 21 into, the tank B. In the same 5 manner, when the valve I8 moves to the right,

a passage is, formed between the central piston I3 and the right end piston 25 to the annular port29 connected with the exhaust opening 39. Thus, oil to the right of the piston I2 as" the 5 piston moves to the right can be expelled through the pipe I4 and the exhaust opening 30 into the tank B.

I have devised a manner of: changing the positionof the valve I8 whichacts automatically to reverse the direction of travel of the-piston l2. This action is accomplished hydraulically in a simple manner which will behereinafter set forth. 1

The end pistons 25 and 528 of the .valve I8 are hollowedout as illustrated'to accommodateresilient coil springs 32. Each end of the valve cylinder 23 is enlarged in diameter to accommodate a narrow auxiliary piston. One auxiliary piston 33 is positioned in the left end of the cylinder 23, and another similar auxiliary piston 34 ispositioned in the right endof the cylinder 23.: An axially projecting rod 35 extends from each of these pistons, and acts as a guide for the coil spring 32 adjacent that piston. -A lug I 36 is centrally positioned on the 'oppositeface of each auxiliary piston'from the arm 35, to keep the piston slightly spaced from the end 31 of the valve cylinder 23.

a A pipe 38 opens into the cylinder D at a point spaced slightly more than the wid h 0f the D ton I2 from the left end of the cylinder D, and connects with a port 39 which is connected through a passage 43 to the extreme end of the V A similar pipe 42 opens into 3 valve cylinder 23. the cylinder D at a point spaced slightly more than the width of the piston I2 from the right end of the cylinder, and connects-with a port.

43 which in turn is provided with a passage 44 to the extreme right end of the cylinder 23. The

pi'pes 38 and 42 are termed control pipes, as they control-themoveinent of the valve I8.

When the valve I8 is in the position illustrated in Figure 2 of the drawings, there is high pressure in the pipe I4 and in the right end of the cylinder D, tending to force the piston I2 to the left. This high pressure is also transmitted through the pipe -42 to the extreme right end of the valve cylinder 23, acting in the space 45 between the'piston 34 and the end 31 of the cylinder 23. The high pressure oil is also permitted to flow through a small passage 46 through the end piston 25. Thus, high pressure is equalized on both sides 'of the auxiliary piston 34, and the auxiliary piston is positioned in the extreme endof the cylinder 23, being forced into this position by the light coil spring 32. High pressure .acts both upon the right side of the ,central piston I9, andthe area at the right endof the valve 18. The pressure to the left'upon the'central piston I9 is equalized by the pressure to the right.

upon the end piston 25, andthe valve I8 is held to the left in the position illustrated by the pres sure acting on the end of the valve I8;

As the piston I2 moves to the left, the passage 4'! acts to conveyexhaust pressure through the of its stroke, the piston passes the opening of the control pipe '38 and subjects this'pipe to high pressure. This high pressure is transmitted to the extreme left end of the valve cylinder 23 through the passage 48, and the auxiliary piston 33 compresses the coil'spring 32 and bears against the left end'of' the valve I8. As the large area of the auxiliary piston 33 is acting against'the small area at the right end of the valve I8, this valve willbe forced to the right, reversing the pressure to the left side of the piston I2 to force 7 I the piston toward the right in the cylinder D.

It may be seen that-if the auxiliary pistons 33 and formed a part of the valve I8, the pressure on each side of the valve, whenthe same is moved in-center position, would be equalized and therefore would not move. The valve I8,'however, is moved by the pressure acting in the space 48 against one sideof the auxiliary piston 33 and movement of the valve I8 is resisted only by the pressure against the end piston 25 of the valve I8. As the valve I8 ismoved slightly beyond center position, the high pressure oil entering the valve A through the port 24 enters the space between the end piston 26 and the center piston I9.

The exhaust ports 2'! and 38 are momentarily closed. High pressure oil is thenfree to pass through the passage 41 into the'space between the end piston'26 and the auxiliary piston 33. The pressure on either side of the auxiliary piston 33 quickly becomes equalized. The spring 32 between the piston 26 and the auxiliary piston 33, which has been compressed by the pressure of the oil in the space 23, immediately expands when the pressure on either side of the auxiliary piston 33 is equalized. The expansion of this spring 32 tends to force the valve I8 and the auxiliary piston 33 apart, moving the valve I8 to the right and the auxiliary piston 33 to the left. The valve I8 is in this way thrown into its extreme 10 position, opening a passageway from the inlet port 24 connected with the pump supply through the pipe I3 to the left end of the cylinder D. It is obvious that as the valve I8 moves past center position, the high pressure is cut off from the right end of the cylinder D and of the valve A. The high pressure on the left end of the valve I8 holds the valve in its extreme right-hand position during the movement of the piston I2 to the right.

The reversal of the valve A when the piston I2 in the cylinder D reaches the right extremity of its stroke, is accomplished in the manner identical to the movement described above. When the piston I2 moves past the opening in the cylinder D of the pipe 42, high pressure oil passes through the pipe 42 and into the space 45 between the auxiliary piston 34 and the end wall 31 of the cylinder 23. The auxiliary piston 34 moves to the left, compressing the spring 32 between the auxiliary piston 34 and the end piston 25 of the valve I8. The rod 35 strikes against the valve I8, forcing the same to the left. As the valve I8 moves past center position, high pressure oil is allowed to pass through the passage 46 and into the space between the end piston 25 of the valve I8 and the auxiliary piston 34. The pressure on the opposite sides of the auxiliary piston 34 is in this way equalized and the spring 32 expands, forcing the valve I8 in its extreme left- 40 hand position, and forcing the auxiliary piston 34 to the right. Pressure is in this manner out off from the left-hand end of the cylinder D and the left end of the valve I8 and the piston I2 in the cylinder D begins to move to the left.

The auxiliary pistons 33 and 34 are effective only when the position of the valve I8 is being changed. During the remainder of the cycle of operation, the pressure on both sides of each of these pistons is equalized. The comparatively large diameter of the auxiliary pistons 33 and 34 with respect to the valve I8, insures the movement of the valve I8 as one of the springs 32 expands, as the valve I8 will move more readily than the auxiliary pistons 33 or 34. The spring 32 provides a source of power necessary to throw the valve I8 into one position or the other over the center position. The size of the passages through the end pistons must be correctly determined as high pressure must enter between the auxiliary piston 33 and the valve l8 before the position of the valve 58 has been changed sufiiciently to reduce the pressure through the pipe 38 or through the pipe 42 to exhaust pressure. This is true for it may be seen that after one of the springs 32 acts to move the valve I8 into one extreme position or the other, there is a short interval of time when both the space 48 between the auxiliary piston 33 and the end wall 31 and the space 45 between the auxiliary piston 34 and the other end wall 3'1, are subjected to exhaust pressure.

When the valve I8 is in its extreme left-hand position and is moved to the right bythe auxiliary piston 33, as soon as the pressure on each side of the auxiliary piston 33 has been equalized acting to throw the valve I8 to its extreme right-hand position, the portion of the cylinder D to the right of the piston I2 is subjected to exhaust pressure. Consequently until the piston I2 covers or passes the opening of the pipe 38 into the cylinder D, the space 48 between the auxiliary piston 33 and the end wall 31 will be subjected to exhaust pressure. This is also true when the valve I8 reverses into the other extreme position. The springs 32 are therefore very necessary in changing position of the valve I8 and are efiicient in accomplishing this function.

Unless the parts of my device are properly designed, the valve I8 might not operate properly. When this valve moves from one position to another, and the pressure on opposite sides of the piston valve I8 is substantially equalized, one of the sprnigs 32 is compressed. For example, when the piston I2 moves to the right, from the position shown in Figure 2, the spring at the left end of the valve I8 is compressed. The piston I2 has uncovered the opening of the tube 38, and high pressure is transmitted to space 48 on the left side of piston 33. Exhaust pressure is still found in cylinder 23 tothe right of piston 33. Piston 33 moves to the right, compressing spring 32 adjacent the same, and moving valve I8 into central position. The pressure on either side of the piston 34 has been equalized, and spring 32 at the right end of valve I8 is not compressed. At this point, pressures on all sides of the valve I8, and pistons 33 and 34 become equalized. The compressed spring 32 tothe left of the valve I8 forces the valve I8 to the right, reversing the flow of liquid into cylinder I8.

When the spring 32 expands, most of the movement resulting therefrom is on the part of the valve 58, as the spring 32 bears equally upon two members, I8 and 33, which are difierent in area. The piston 33, being larger in diameter, resists movement more than the valve I8 which is of smaller diameter. The valve I8 may also be lighter in weight than the pistons 33 and 34, which would also make the valve move instead of the piston. Furthermore, because of the large volume of the chamber D it will be a considerable time before the fluid in D, 38 and 48 can exhaust through I4, 22, 29 and 39 when valve I8 has slightly opened, so that the pressure in 48 will not drop to balance the two sides of piston 33 until the spring 32 has had time to shift the valve I8 to the right.

In order to prevent excess pressure within the valve A, if for some reason the piston I2 or the rod I5 or plunger IB is obstructed, I provide a pressure relief valve. A passage 58 connects the annular port 24 with the cylinder 52 of the pressure relief valve plunger 53. The valve 53 is ordinarily held against a tapered seat 54 adjacent the passage 50 by means of a compression spring 55. A passage 56 connects the ports 39 and 43 of the pipes 38 and-42 with the relief valve cylinder 52. Ball check valves 5'! and 58 close the end of the passage 56. The check valves 57 and 58 are held in a position to close the passage 56 normally by the high or exhaust pressure of the oil within the ports 39 and 43. A portion of the plunger 53 is of reduced diameter so that the passage 58 is normally connected with the opening 59.

When the piston I2 is obstructed while traveling in one direction or the other, an excessive pressure is built up by the constant speed pump C in the valve A. This pressure is communicated through the passage 58 to the relief valve 53. When the pressure builds up sufliciently the valve CPL plunger 53 is raised against the tension of the spring 55. The passage 56 is in this way subjected to high pressure by the raising of theplunger 53. One or. the other of the ports 39 or 43 is already subjected to high pressure as either the pipe 38 or the pipe 42 communicates with the high pressure end of the cylinder D. The ball check 51 or 58 9 adjacent the port 39 or 43 which is already subjected to high pressure will not be moved as the high pressure will be equalized on opposite sides of the ball. The ball check 51 M58 adjacent the port 39 or 43 which is subjected to exhaust pressure, however, will be moved into the dotted position illustrated in the drawings, closing ed the end of the pipe 38 or 42 communicatingbetween this port and the cylinder D. For example, if the valve I9 is in the position illustrated in'Figure 2 of the drawings at the extreme left position, and the piston H in the cylinder D is moving to the left, if an obstruction should prevent further movement of the piston l2, an excessive pressure will be built up within the valve A and the right end of the cylinder D. This excessive pressure will tend to raise the valve plunger 53 from its 5 seat until the passage 56 is in communication with the high pressure within the valve. The ball check 58 will not be moved from its seat as the port 43 and the pipe 42 are in communication 'will then close the opening to the pipe 38 and the space 48 between the auxiliary piston 33 and the end 31 of the valve cylinder, will be in communication with high pressure oil through the passage 40. The auxiliary piston 33 will then move to the right and will force'the valve |8 to the right, acting in amanner which has been heretofore described to reverse the position of the valve l8 and cause the piston l2 to move in the opposite direction. Therefore, when the piston I2 is obstructed from moving in one direction, the valve A will act to automatically reverse the pressure to cause the piston to move in the opposite direction.

A means is also provided to produce any desirable interval of rest while the piston-|2 is at one end of its stroke. This interval of rest 'is controlled by means of a control valve 60 and a metering valve 6|. The control valve 60 is positioned in a control valve cylinder 62. The control valve .60 is a two-lobe valve with a restricted connecting portion 63. The ports 29 and 22 are connected through the control valve cylinder 62 and these ports are separated by means of a sleeve 64 fitting about the connecting portion 63. An oil tank 65is connected by means of the pipe 66 to one end of the cylinder 62 while the other end of the cylinder is open; cylinder 62 communicating with the tank 65,

, is provided with an opening 61 leading to the One end. of the valve 60 metering valve 6|. 7 within this end of the cylinder 62, is provided with a passage 68 connecting the end of the cylinder 62 with the port 22 when the control valve isin the position illustrated in Figure 2 of the drawings. An exhaust opening 69 is provided in the cylinder 62 near the opening61 connecting with the metering valve 6|. 7

-,When the valve |8 isin the position illustrated in the drawings, the port 22 is subjected to high The end of the oil pressure from the pump. The oil passes into the control cylinder 62 and forces the piston plunger 66 into the position illustrated in Figure 2 of the drawings or into its extreme righthand position, in which position the adjustable washer 10 which is connected to the plunger piston 60 by means of the threaded stud12, bears against the open end of the cylinder 62. The plunger piston 6|] is thus moved so that the end lobe 1| uncovers the exhaust port 69. The oil from the pump is thus 'free to pass out through the exhaust port 69. At the same time, however, a portion of the oil passes through the passage 68 and into the tank 65, as the port 69 is too small to permit exhausting of oil pressure without creating suiiicient back pressure to cause flow of oil intothe tank 65. This back pressure is not sufficient to move the piston |2. Air may be readily expelled through the check '.valve '13.

However, when the tank 65 gets full, the pressure of the oil closes the check valve 13. A pressure is thus built up in'the tank 65 which is equal to the pressure in the port 22 and as the pressure within the tank 65 may act against the entire end of the plunger piston 60, while the e t pressure from the annular port 22 acts only against the annular surface about the connecting portion 63' of the plunger valve 66, this piston valve is moved to the left, covering up the exhaust opening 69. The movement of the valve 60 to the left continues'until the opening 68' of the passage 68 through the valve 60 is almost entirely closed. The end lobe 1| of the piston plunger valve 66 covers both the exhaust opening 69 and .the opening 61 to the metering valve 6| when in 1 this position. The oil from the pump then passes through the pipe I4 into the cylinder D .and acts to move the piston |2to the left. When the piston reaches the extreme left-hand end of its stroke and starts to reverse, the annular port 26 will be subjected to high pressure and the port 22 will be subjected to exhaust pressure. The high pressure in the port 20 will act against the left end lobe 16 of the plunger piston 66, forcing the piston into a position wherein the end lobe 1| of the plunger piston 60 uncovers the opening 61. tion, the passage 68 remains closed by the sleeve 64, but the opening 61 is uncovered by the right end lobe 1|. Oil is thus free to drain from the tank 65 out through the opening 61. The speed with which the oil will drain from the tank 65,, however, depends upon the position of the manually positioned metering valve 6| which partially closes the opening 61. If the metering valve6| entirely closes the opening 61, no'oil may drain fromthe tank 65 and when the valve I9 reverses its position, no moreoil can pass into the tank 65 so that theplunger piston 60 moves until the seen that if the metering valve 6| is so positioned 1 that a large amount of the: oil in the tank 65 is drained during thestroke of the piston 12', a longer time will be required to refill the tank and accordingly, a longer interval of rest of the piston I2 will be provided than will occur if only a small amount of oil is drained from the tank 65.

When the plunger piston 66 is in this'poslve A pivoted arm 1'! is illustrated in dotted outline in Figure 2 of the drawings. operated by the metering valve Bl the raising and lowering of the valve 6| acting to pivot the arm 11. When the hole 61 is entirely closed by the lowering of the valve 6!, the arm Tl pivots over the washer iii to prevent outward movement of the piston plunger 68. The exhaust port 69 is allowed to remain open until the arm TI releases 10 the washer l9, thus permitting an indefinite period of rest. When the valve BI is raised slightly, the arm 71 pivots out of the line of movement of the washer T0.

In this manner, I have provided a valve which 15 acts to automatically reverse the direction of the piston within the cylinder D at the end of each stroke. My valve also acts to provide an interval of rest at the end of each stroke if it is desired and this interval may be varied at will to regulate 20 the speed of coal feed. My Valve A also acts to 30 sure relief plunger 53 and may comprise a pair of contacts 78 which are positioned slightly above the top of the relief valve plunger 53. A top portion of the plunger rod 53 is insulated from the remainder of the plunger 53 by an insulated por- 35 tion l9 and the alarm is so devised, that when the Cir plunger 53 raises due to excessive pressure in the valve A, a contact is formed between the contact members E8 which closes the circuit through a battery 89 or other source of electrical supply to a suitable alarm 82. Thus, each time the movement of the piston 12 is reversed due to an obstruction which blocks the movement of the piston 52, an alarm is sounded which notifies the operator of the stoker of this fact.

I have described my invention as being particularly suited for use in combination with stoker cylinders. I wish to have it understood, however, that my valve A may be used wherever a reversing valve of this type is desirable, wherein the movement of a piston within a cylinder is to be automatically reversed at the end of each stroke.

In accordance with the patent statutes, I have described the principles of operation of my invention, and while I have endeavored to set forth the best embodiment thereof, I desire to have it understood that this is only a means of carrying out my invention and that obvious changes may be made within the scope of the following claims without departing from the spirit of the inven- 60 tion.

I claim: I 1. A controlling device for hydraulically operated pistons in a cylinder including, a regulating valve interposed between a source of supply 65 of fluid pressure and the cylinder, said valve 75 change position and to automatically reverse the v comprising a unitary three piston reversing valve having hollow ends, coil springs adapted to fit into said ends, auxiliary pistons associated with This arm 11 is movement of the piston in the cylinder by hydraulic pressure.

2. A controlling device for hydraulically operated pistons-in a cylinder including, a regulating valve interposed between the source of fluid pressure and the cylinder comprising, a Valve piston operable to direct the pressure to one extreme end or the other of the cylinder and to connect the extreme end not subjected to pressure with the exhaust, auxiliary pistons slidable by hydraulic pressure at either end of said valve piston, by-pass means for equalizing the hydraulic pressure on either side of said valve piston, resilient means interposed between said valve piston and said auxiliary pistons, and conduits exposed to high pressure when the first named piston approaches the end of its stroke for forcing one of said auxiliary pistons against said valve piston to move the valve piston in a manner to reverse the flow of pressure to said cylinder.

3. A controlling device for a hydraulic piston in a cylinder including, a piston valve operable to reverse the flow of oil pressure to the cylinder, conduits connecting said valve with extreme ends of said cylinder alternately connecting the cylinder with high pressure and exhaust, auxiliary pistons operable to move said valve piston, compressible means between said valve piston and said auxiliary pistons, and means for communicating hydraulic pressure against one of said auxiliary pistons at a desired point in the stroke of the first named piston to move said valve piston and to reverse the flow of pressure in said cylinder.

4. A controlling device for a hydraulic pisto in a cylinder including, a piston valve operable to reverse the flow of pressure from a source of fluid pressure to opposite extreme ends of said cylinder, simultaneously connecting the other end to exhaust pressure, auxiliary pistons adapted to bear against said piston valve to move the same, resilient means between said piston valve and said auxiliary pistons, means for equalizing the hydraulic pressure on opposite sides of said piston valve and auxiliary valves, and by-pass means communicable with high hydraulic pressure when the first named piston reaches a desired point in its stroke to unbalance the hydraulic pressure on opposite sides of one of said auxiliary pistons to cause said auxiliary piston to move said piston valve to reverse the pressure flow in said cylinder.

5. A controlling device for a hydraulically operated piston in a cylinder comprising, a Valve interposed between a source of fluid supply and the cylinder to reverse the flow of high pressure and exhaust pressure from one extreme end to the other thereof, auxiliary pistons slidably mounted at either end of said valve to operate the same, resilient means interposed between said valve and said auxiliary pistons, means for equal izing high hydraulic pressure on either side of one of said auxiliary pistons, means for equalizing loW pressure on either side of the other of said auxiliary pistons, and means for introducing high pressure on one side only of the last named auxiliary piston at a predetermined point in the stroke of the hydraulic piston to move said valve to reverse the fluid pressure to the cylinder.

6. A controlling device for a hydraulically operated piston in a cylinder including, a balanced valve interposed between a source of fluid supply and said cylinder to reverse the flow of high and exhaust pressure to extreme ends of said cylinder, auxiliary pistons slidably mountedat either end of said balanced valve of larger diameter than said valve, resilient means interposed between said valve and said auxiliary pistons, means for equalizing hydraulic pressure onopposite sides of said auxiliary pistons, and means controlled by the first named piston to introduce pressure to a greater area in said valve and auxiliary pistons at a predetermined point in the stroke of the first named piston than is a holding the valve against movement, to cause the valve to reverse the flow.

'7. A controlling device for a hydraulically operated piston in a cylinder including, a'fiuid pressure reversing valve for said cylinder, auxiliary pistons slidably mounted on either side of said valve to move said valve, springs interposed between said auxiliary pistons and said valve, means for equalizing hydraulic pressure on opposite sides of said auxiliary pistons, means controlled by the movement of the first named piston for introducing hydraulic pressure on one side of one of said auxiliary pistons to compress the springbetween this auxiliary piston and the valve, the compression of 'the'spring and the movement of the auxiliary piston moving said reversing valve.

8. A controlling device for a hydraulically operated pisto'nin a cylinder including, a valve operable by normal hydraulic pressure when said piston reaches a predetermined point in the cylinder, and interposed between the source of fluid pressure and thecylinder for reversing the pres-, sure flow thereof at the completion of each stroke of the piston, a relief valve operable under excessive pressure, valve operating pistons for moving said first named valve, and a by-passfrom; said relief valve to introduce fluid pressure to one of said valve operating pistons to move said valve. 9. A controlling device for a hydraulically opera ated-piston in a cylinder including, a valve oper able by normal hydraulic pressure when said piston reaches a predetermined point in the cylinder and interposed between a source of pressure supply and the cylinder to reverse the flow thereof said pistons will operate to move said reversing valve when said relief valve is opened.

HAROLD S. MORTON. 

